1. Field of the Invention
The present invention relates to a thermosetting resin composition for an interlayer insulating material having low water absorption, a low dielectric constant and low dielectric dissipation factor, and excellent adhesion to a substrate and a conductor in a build-up type multilayer printed wiring board in which conductor circuit layers and insulation layers are alternately accumulated, and to a multilayer printed wiring board using the same.
2. Description of the Related Art
Attention has recently been directed to a build-up type manufacture technique in which an organic insulating layer and a conductor layer are alternately accumulated on a conductor layer of an inner layer circuit board as a method of manufacturing the multilayer printed wiring board. For example, a method of manufacturing a multilayer printed wiring board has been proposed, in which after an epoxy resin composition is applied to an inner layer circuit board having a circuit formed thereon, heated and cured, an uneven roughened surface is formed on the surface of the obtained insulating layer by a roughening agent, and subsequently, a conductor layer is formed by plating (refer to, for example, Jpn. Pat. Appln. KOKAI Publication Nos. 7-304931 [claims] and 7-304933 [claims]).
A method of manufacturing a multilayer printed wiring board has been proposed, in which after an epoxy resin adhesion sheet is laminated on an inner layer circuit board having a circuit formed thereon, heated and cured, an uneven roughened surface is formed on the surface of the obtained insulating layer by a roughening agent, and subsequently, a conductor layer is formed by plating (refer to, for example, Jpn. Pat. Appln. KOKAI Publication No. 11-87927 [claims]).
However, these manufacturing methods form the roughened surface using the roughening agent, and form the conductor layer using the plating. None of the inventions refers to the water absorption, dielectric constant or dielectric dissipation factor essential for the high density and high speed of the latest electronic equipment. Moreover, the obtained insulating layer has actually high water absorption, and a comparatively high dielectric constant and dielectric dissipation factor.
On the other hand, a process for forming the roughened surface on the surface of the insulating layer described above to form the conductor layer by electroless plating adopts the following process. That is, the whole surface of the cured insulating layer is generally swelled by an organic solvent such as N-methyl-2-pyrrolidone, N,N-dimethylformamide and methoxypropanol, and an alkaline aqueous solution or the like such as caustic soda and caustic potash. Subsequently, the surface is roughened by using an oxidizer such as a dichromate, a potassium permanganate, ozone, hydrogen peroxide/sulfuric acid or nitric acid. Then, the surface is immersed in an aqueous solution containing a catalyst for plating to adsorb the catalyst to the surface, and is immersed in a plating liquid in which metal is solubilized to deposit the plating.
However, since most chemicals to be used exist in the state of an aqueous solution in the process, a sufficient roughened shape is not obtained after all when the hydrophobicity of the insulating layer is increased. As a result, there have been problems in that the adhesion and contact of conductor plating are not obtained.